jfcamaro

hello
my name is jean-francois
i dont own a corvette but a old 75 camaro
i plan to modify my front suspension with the c4 front suspension

here is my question:

- the 84-87 hub to hub (HH) distance is 59"
- wheels are 16x8,5 0ffset 32 mm (1,25") and backspacing 6"

- the 88up hub to hub (HH) distance is 60,5"
- wheels are 17x9,5 Offset 56 mm (2,125") and backspacing 7,45"


Let say I want to use the 17" wheels on the 84-87 front suspension:

- 16" wheels, 8,5 wide and 6 backspace, so the front spacing is (8,5-6)= 2,5"
By adding 2,5+2,5+59= 64"
The wheels to wheels outside distance is 64"

- do the same maths with the 17"
9,5 wide and 7,45 backspace, so the front spacing is (9,5-7,45)= 2.05 "
By adding the 2.05+2.05+59= 63.1"
The wheels to wheels outside distance is now 63.1"

So i need 0,45" wheel spacer on each side to get the correct distance?

Is this right? Because I read need the 1" to 1,25" wheel spacer
So I dont know how people got those number.


If correct, i will do the same calculationt with other wheels dimension

DanZ51

I have to ask: If you're adapting a C4 suspension to your Camaro, wouldn't it be wiser to get the suspension installed first then measure your fender clearance? Your backspacing (offset) could be varied to clear the Camaro.

WVZR-1

Is this maybe the same '75 that a "friend" asked about the rear IRS?

Where did your "hub to hub" dimensions come from and those are "wheel mating flange to wheel mating flange"?

You do it this way on the front for starters and move on from there. You measure your Camaro front width "outer finished surface of the rotor to the outer finished surface of the other rotor" and compare that to the widths of the '87 and earlier production, then again compare that dimension to the widths of the '89 + production. Ideally you might want different dimensions but these would be easier for comparisons only.

I can't help you with either of the Corvette dimensions but that's where I'd start and I'd want to do the measurements myself or by someone that actually understood what you wanted!

You need a couple "local" volunteers!

I see what you've attempted with your numbers but it's just not the way that it's done. If you insist on doing wheels first you set up a pair of tire/wheel combinations that you intend to do and you measure mounting flange to mounting flange and do what's needed from there. Are you wanting to use a specific Corvette wheel?

An easier comparison for you would be to use two 9 1/2" wheels, an early 16 X 9 1/2" wheel is 38mm offset and the later 17 X 9 1/2" wheel is 56mm offset the difference required to place the footprint of the late equal to the early is 18mm or 3/4" approximately. The later offset when mounted on an early car will interfere with the control arms on very tight lock to lock crank of the wheel with out spacers of some sort.

If you're going to the extreme of the IFS on the Camaro I can't image you're wanting to use an OE Corvette wheel.

Your other problem is your confusing offsets and back-spacing, they can be calculated from one another but you need to use "total wheel width" for the calculations. A 9 1/2" advertised wheel is actually closer to 10 1/2" wide. Any advertised width wheel you choose to compare to anything else and intend to use offset you need to use the "total wheel width"!

Your references to front spacing + back-spacing need to equal "total wheel width" NOT advertised.

For your particular build you need to work with a tire/wheel combination to start, not just wheels. The tire side walls are your concern.

jfcamaro

no, im not the same guy who ask about the rear suspension

i got the hub to hub measurement from
http://www.ikerds.net/front-suspension-complete.html
I meet the guy at carlisle and he gave me sheet with dimension on it.

what i try to figure out is can i use the 17" corvette wheel without modifying the rear differential or using too wide wheel spacer.

WVZR-1

You don't mention where you're located but I believe I'd probably try to roundup some 275/17 scuffs on some 9 1/2" wheels and check the fit on the rear. I would doubt the fit unless the wheel-houses have been altered.

Where are you located?

If this helps you at all and since you mentioned "front spacing" which I don't use or often relate to:

A 17 X 9 1/2 56mm offset with a 275 tire mounted from the wheel mounting flange to the tire outside sidewall is 3 1/2" +/- very little.